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Publication
Journal: Materials
May/11/2019
Abstract
In this work, a novel boehmite (BA)-embedded organic/inorganic nanocomposite coating based on cycloaliphatic epoxy oligosiloxane (CEOS) resin was fabricated applying UV-induced cationic polymerization. The main changes of the material behavior caused by the nanofiller were investigated with regard to its photocuring kinetics, thermal stability, and glass transition. The role of the particle surface was of particular interest, thus, unmodified nanoparticles (HP14) and particles modified with p-toluenesulfonic acid (OS1) were incorporated into a CEOS matrix in the concentration range of 1-10 wt.%. Resulting nanocomposites exhibited improved thermal properties, with the glass transition temperature (Tg) being shifted from 30 °C for unfilled CEOS to 54 °C (2 wt.% HP14) and 73 °C (2 wt.% OS1) for filled CEOS. Additionally, TGA analysis showed increased thermal stability of samples filled with nanoparticles. An attractive interaction between boehmite and CEOS matrix influenced the curing. Real-time infrared spectroscopy (RT-IR) experiments demonstrated that the epoxide conversion rate of nanocomposites was slightly increased compared to neat resin. The beneficial role of the BA can be explained by the participation of hydroxyl groups at the particle surface in photopolymerization processes and by the complementary contribution of p-toluenesulfonic acid surface modifier and water molecules introduced into the system with nanoparticles.
Publication
Journal: Frontiers in Plant Science
January/24/2021
Abstract
Nematicidal potential of essential oils (EOs) has been widely reported. Terpenoids present in most of the essential oils have been reported responsible for their bioactivity though very less is known about their modes of action. In the present study, an in vitro screening of nine Eos, namely, Citrus sinensis (OEO), Myrtus communis (MTEO), Eucalyptus citriodora (CEO), Melaleuca alternifolia (TEO), Acorus calamus (AEO), Commiphora myrrha (MREO), Cymbopogon nardus (CNEO), Artemisia absinthium (WEO), and Pogostemon cablin (PEO) against Meloidogyne incognita revealed OEO, CNEO, and TEO as most effective with LC50 39.37, 43.22, and 76.28 μg ml-1 respectively. EOs had varying compositions of mono- and sesquiterpenes determined by gas chromatography-mass spectrometry (GC-MS) analysis. The in silico molecular interactions screening of major EO constituents and the seven selected target proteins of the nematode indicated highest binding affinity of geraniol-ODR1 (odorant response gene 1) complex (ΔG = -36.9 kcal mol-1), due to extensive H-bonding, hydrophobic and π-alkyl interactions. The relative binding affinity followed the order: geraniol-ODR1 > β-terpineol-ODR1 > citronellal-ODR1 > l-limonene-ODR1 > γ-terpinene-ODR1. Taken together, the cumulative in vitro and computational bioefficacy analysis related to the chemoprofiles of EOs provides useful leads on harnessing the potential of EOs as bionematicides. The insight on biochemical ligand-target protein interactions described in the present work will be helpful in logical selection of biomolecules and essential oils for development of practically viable bionematicidal products.
Keywords: Meloidogyne incognita; gas chromatography-mass spectrometry analysis; molecular docking; odorant response gene 1; volatile oils.
Publication
Journal: Advanced healthcare materials
July/10/2019
Abstract
Wound healing is a complex and sequential biological process that involves multiple stages. Although various nanomaterials are applied to accelerate the wound healing process, only a single stage is promoted during the process, lacking hierarchical stimulation. Herein, hollow CeO2 nanoparticles (NPs) with rough surface and l-arginine inside (Ah CeO2 NPs) are developed as a compact and programmable nanosystem for sequentially promoting the hemostasis, inflammation, and proliferation stages. The rough surface of Ah CeO2 NPs works as a nanobridge to rapidly closure the wounds, promoting the hemostasis stage. The hollow structure of Ah CeO2 NPs enables the multireflection of light inside particles, significantly enhancing the light harvest efficiency and electron-hole pair abundance. Simultaneously, the porous shell of Ah CeO2 NPs facilitates the electron-hole separation and reactive oxygen species production, preventing wound infection and promotion wound healing during the inflammation stage. The enzyme mimicking property of Ah CeO2 NPs can alleviate the oxidative injury in the wound, and the released l-arginine can be converted into nitric oxide (NO) under the catalysis of inducible NO synthase, both of which promote the proliferation stage. A series of in vitro and in vitro biological assessments corroborate the effectiveness of Ah CeO2 NPs in the wound healing process.
Publication
Journal: Nanomaterials
May/15/2019
Abstract
The main objective of this study is to evaluate the regenerative effect of functionalized CeO2±δ nanoparticles with a mass fraction of 0.89% of NiO and 1.1% of PdO in adsorption and subsequent decomposition of n-C7 asphaltenes in steam gasification processes. During each regeneration cycle, the adsorption capacity and the catalytic activity of the nanoparticles were evaluated. To estimate the adsorption capacity of the nanoparticles, adsorption kinetics were studied at a fixed concentration of n-C7 asphaltenes of 10 mg·L-1 as well as adsorption isotherms at three different temperatures at 25 °C, 55 °C, and 75 °C. To evaluate the catalytic activity, the loss of mass of the nanoparticles was evaluated by isothermal conversions with a thermogravimetric analyzer at 230 °C, 240 °C, and 250 °C, and at non-isothermal conditions involving a heating from 100 °C to 600 °C at a 20 °C·min-1 heating rate. The asphaltenes showed a high affinity for being adsorbed over the nanoparticles surface, due to the nanoparticles-asphaltene interactions are stronger than those that occur between asphaltene-asphaltene, and this was maintained during nine evaluated regeneration cycles as observed in the Henry's constant that increased slightly, with changes of 21%, 26% and 31% for 25 °C, 55 °C and 75 °C. Polanyi's adsorption potential decreases by 2.6% for the same amount adsorbed from the first cycle to the ninth. In addition, the catalytic activity of the nanoparticles did not change significantly, showing that they decompose 100% of the n-C7 asphaltenes in all cycles. However, the small decrease in the adsorption capacity and catalytic activity of the nanoparticles is mainly due to the presence and change in concentration and ratio of certain elements such as oxygen, iron or others at the surface of the nanoparticle as shown by X-ray photoelectron spectroscopy (XPS) analyses. Thermodynamic parameters of adsorption such as Δ H a d s o , Δ S a d s o , and Δ G a d s o and the effective activation energy (Ea) were calculated to compare adsorptive and catalytic performance during each cycle. There is an increase of 9.3% and 2.6% in the case of entropy and enthalpy, respectively, and a decrease of 0.5%, 3.1% and 6.5% for 25 °C, 55 °C and 75 °C respectively for the Gibss free energy from cycle 1 to cycle 9. It was found that these parameters are correlated with the Ce concentration and oxidation state ratios (Ce3+/Ce4+ couple) at the surface.
Publication
Journal: Journal of Personality and Social Psychology
March/14/2019
Abstract
In 1992, the Study of Mathematically Precocious Youth (SMPY) surveyed 714 first- and second-year graduate students (48.5% female) attending U.S. universities ranked in the top-15 by science, technology, engineering, and mathematics (STEM) field. This study investigated whether individual differences assessed early in their graduate school career were associated with becoming a STEM leader 25 years later (e.g., STEM full professors at research-intensive universities, STEM CEOs, and STEM leaders in government) versus not becoming a STEM leader. We also studied whether there were any important gender differences in relation to STEM leadership. For both men and women, small to medium effect size differences in interests, values, and personality distinguished STEM leaders from nonleaders. Lifestyle and work preferences also distinguished STEM leaders who were more exclusively career-focused and preferred to work-and did work-more hours than nonleaders. Also, there were small to large gender differences in abilities, interests, and lifestyle preferences. Men had more intense interests in STEM and were more career-focused. Women had more diverse educational and occupational interests, and they were more interested in activities outside of work. Early in graduate school, therefore, there are signs that predict who will become a STEM leader-even among elite STEM graduate students. Given the many ways in which STEM leadership can be achieved, the gender differences uncovered within this high-potential sample suggest that men and women are likely to assign different priorities to these opportunities. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
Publication
Journal: BioMed Research International
July/7/2015
Abstract
Citronella essential oil (CEO) has been reported as an excellent mosquito repellent; however, mild irritancy and rapid volatility limit its topical application. It was aimed to develop a nonirritant, stable, and consistent cream of CEO with improved residence time on skin using an industrial approach. Phase inversion temperature technique was employed to prepare the cream. It was optimized and characterized based on sensorial evaluation, emulsification, and consistency in terms of softness, greasiness, stickiness, and pH. The optimum batch (B5) was evaluated for viscosity (90249.67±139.95 cP), texture profile with respect to firmness (38.67±0.88 g), spreadability (70.33±0.88 mJ), and extrudability (639.67±8.09±0.1 mJ) using texture analyzer along with two most popular marketed products selected as reference standard. Subsequently, B5 was found to be stable for more than 90 days and showed enhanced duration of mosquito repellency as compared to CEO. HS-GC ensured the intactness of CEO in B5. Investigated primary irritation index (PII 0.45) positioned B5 into the category of irritation barely perceptible. The pronounced texture profile and stability of B5 with extended residence time and less PII revealed its potential application in industry and offered a promising alternative to the marketed products of synthetic origin.
Publication
Journal: Food Chemistry
November/7/2019
Abstract
The effect of four different coating dispersions including chitosan, clove essential oil, chitosan nanoparticles and clove essential oil loaded chitosan nanoparticles (CEO-ChNPs or encapsulated oil) was investigated on shelf life and quality of minimally processed pomegranate arils during storage at 5 °C. Among tested dispersions, CEO-ChNPs extended aril shelf life for 54 days while uncoated arils became unusable at day 18 due to the incidence of fungal decay. At the end of storage, CEO-ChNPs could significantly maintain microbial quality, weight, total soluble solid, titratable acidity, pH, total phenol and total anthocyanin content, as well as antioxidant activity and sensory quality in pomegranate arils coated with CEO-ChNPs compared to uncoated arils, however only some of mentioned parameters maintained significantly in arils coated with other dispersions (P < 0.05). According to these results, CEO-ChNPs were the most effective coating for extending shelf life and controlling undesirable microbial, physicochemical and sensory alterations of pomegranate arils.
Publication
Journal: Nanomaterials
October/1/2019
Abstract
The interesting physicochemical characteristics of nanomaterials (NMs) has brought about their increasing use and, consequently, their increasing presence in the environment. As emergent contaminants, there is an urgent need for new data about their potential side-effects on human health. Among their potential effects, the potential for DNA damage is of paramount relevance. Thus, in the context of the EU project NANoREG, the establishment of common robust protocols for detecting genotoxicity of NMs became an important aim. One of the developed protocols refers to the use of the comet assay, as a tool to detect the induction of DNA strand breaks. In this study, eight different NMs-TiO2NP (2), SiO2NP (2), ZnONP, CeO2NP, AgNP, and multi-walled carbon nanotubes (MWCNT)-were tested using two different human lung epithelial cell lines (A549 and BEAS-2B). The comet assay was carried out with and without the use of the formamidopyrimidine glycosylase (FPG) enzyme to detect the induction of oxidatively damaged DNA bases. As a high throughput approach, we have used GelBond films (GBF) instead of glass slides, allowing the fitting of 48 microgels on the same GBF. The results confirmed the suitability of the comet assay as a powerful tool to detect the genotoxic potential of NMs. Specifically, our results indicate that most of the selected nanomaterials showed mild to significant genotoxic effects, at least in the A549 cell line, reflecting the relevance of the cell line used to determine the genotoxic ability of a defined NM.
Publication
Journal: Virus Genes
December/9/2013
Abstract
Infectious laryngotracheitis virus (ILTV) continues to cause respiratory disease in Egypt in spite of vaccination. The currently available modified live ILTV vaccines provide good protection but may also induce latent infections and even clinical disease if they spread extensively from bird-to-bird in the field. Four field ILTV isolates, designated ILT-Behera2007, ILT-Giza2007, ILT-Behera2009, and ILT-Behera2010 were isolated from cross-bred broiler chickens. The pathogenicity based on intratracheal pathogenicity index, tracheal lesion score, and mortality index for chicken embryos revealed that ILT-Behera2007, ILT-Behera2009 and ILT-Behera2010 isolates were highly pathogenic whereas ILT-Giza2007 was non-pathogenic. To study the molecular epidemiology of these field isolates, the infected cell protein 4 gene was amplified and sequenced. Phylogenetic analysis revealed that ILT-Behera2007, ILT-Behera2009, and ILT-Behera2010 are chicken embryo origin (CEO) vaccine-related isolates while ILT-Giza2007 is a tissue culture origin vaccine-related isolate. These results suggest that CEO laryngotracheitis vaccine viruses could increase in virulence after bird-to-bird passages causing severe outbreaks in susceptible birds.
Publication
Journal: Applied Microbiology and Biotechnology
September/3/2020
Abstract
Candida infections are a significant source of patient morbidity and mortality. Candida albicans is the most common pathogen causing Candida infections. Candida auris is a newly described pathogen that is associated with multi-drug-resistant candidiasis and candidaemia in humans. The antifungal effects of various essential oils and plant compounds have been demonstrated against human pathogenic fungi. In this study, the effect of cinnamon leaf and bark essential oils (CEOs) was determined against both C. albicans and C. auris. The disc diffusion (direct and vapour) and broth microdilution method was used to determine antifungal activity of the EOs against selected strains (C. albicans ATCC 10231, C. albicans ATCC 2091 and C. auris NCPF 8971) whilst the mode of action and haemolysin activity of the CEOs were determined using electron microscopy and light microscopy. Direct and vapour diffusion assays showed greater inhibitory activity of bark CEO in comparison with leaf CEO. The minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) of bark CEO for all tested strains was below 0.03% (v/v), which was lower than the MICs of the leaf CEO (0.06-0.13%, v/v) dependent on the strain and the MFCs at 0.25% (v/v). In the morphological interference assays, damage to the cell membrane was observed and both CEOs inhibited hyphae formation. The haemolysin production assay showed that CEOs can reduce the haemolytic activity in the tested C. albicans and C. auris strains. At low concentrations, CEOs have potent antifungal and antihaemolytic activities in vitro against C. albicans and C. auris.Key points• Essential oils from Cinnamomum zeylanicum Blume bark and leaf (CBEO and CLEO) demonstrated fungicidal properties at very low concentrations.• The antifungal activity of CBEO was greater than that of CLEO consistent with other recent published literature.• The mode of action of CBEO and CLEO was damage to the membrane of C. albicans and C. auris.• Both CBEO and CLEO inhibited the formation of hyphae and reduced haemolysin production in C. albicans and C. auris. Graphical abstract.
Keywords: Antifungal; Antihaemolytic; Candida infections; Cinnamon; Essential oil.
Publication
Journal: Rural and Remote Health
November/25/2016
Abstract
Rural communities continue to experience significant challenges recruiting and retaining physicians. The Community Apgar Questionnaire (CAQ) was developed in Idaho in the USA to comprehensively assess the characteristics associated with successful recruitment and retention of rural physicians. The CAQ has been utilised and validated across the USA; however, its value in rural Australia has not been examined. The objective of this study was to use the CAQ in rural Australia to examine its utility and develop a greater understanding of the community factors that impact general practitioner (GP) recruitment and retention.
The project conducted structured face-to-face interviews with hospital chief executive officers (CEOs) and directors of clinical services (DCSs) from 14 of the 21 (76%) health services that agreed to participate in rural north-eastern Victoria, Australia. The interviews were undertaken to complete the CAQ, which contains 50 questions centred on factors that influence physician recruitment and retention. Once completed, CAQs were scored by assigning quantitative values to a community's strengths and challenges including the level of importance placed on each factor. As such, the most important factors in physician recruitment, whether they are advantages or challenges for that community, were then weighed for their relative importance. Scores were then combined to create a CAQ score. To ensure reliability and validity of the results, three additional CAQs were purposefully administered to key general practices within the region.
The 14 rural communities exhibited cumulative CAQ scores ranging from a high of 387 to a low score of 61. This suggests the tool was sensitive enough to differentiate between communities that were high and low performers in terms of physician recruitment. The groups of factors that had the greatest impact on recruitment and retention were ranked highest to lowest and included medical support, hospital/community support, economic, scope of practice and geographic factors. Overall, the highest individual factors to impact recruitment and retention were perception of quality, hospital leadership, nursing workforce and transfer arrangements. Conversely, the lowest factors and challenges to recruitment and retention were family related, specifically spousal satisfaction and access to schools.
Hume, in rural Victoria, was the first international site to implement the CAQ to differentially diagnose a community's relative strengths and challenges in recruiting and retaining GPs, while supporting health facilities to prioritise achievable goals to improve long-term retention strategies. It provided each community with a tailored gap analysis, while confidentially sharing best practices of other health facilities. Within Hume, open communication and trust between GPs and health facility leadership and nursing staff ensures that GPs can feel valued and supported. Possible solutions for GP recruitment and retention must consider the social, employment and educational opportunities that are available for spouses and children. Participation in the program was useful as it helped health facilities ascertain how they were performing while highlighting areas for improvement.
Publication
Journal: Nanoscale
May/12/2021
Abstract
Obesity is one of the most important public health problems that is associated with an array of metabolic disorders linked to cardiovascular disease, stroke, type 2 diabetes, and cancer. A sustained therapeutic approach to stop the escalating prevalence of obesity and its associated metabolic comorbidities remains elusive. Herein, we developed a novel nanocomposite based on mesoporous silica coated cerium oxide (CeO2) nanozymes that reduce the circulating levels of fatty acids and remarkably improve the metabolic phenotype in a model of obese Zucker rats five weeks after its administration. Lipidomic and gene expression analyses showed an amelioration of the hyperlipidemia and of the hepatic and adipose metabolic dysregulations, which was associated with a down-regulation of the hepatic PI3K/mTOR/AKT pathway and a reduction of the M1 proinflammatory cytokine TNF-α. In addition, the coating of the CeO2 maximized its cell antioxidant protective effects and minimized non-hepatic biodistribution. The one-pot synthesis method for the nanocomposite fabrication is implemented entirely in aqueous solution, room temperature and open atmosphere conditions, favoring scalability and offering a safe and translatable lipid-lowering and antioxidant nanomedicine to treat metabolic comorbidities associated with obesity. This approach may be further applied to address other metabolic disorders related to hyperlipidemia, low-grade inflammation and oxidative stress.
Publication
Journal: Academic Pathology
November/13/2018
Abstract
The 2017 Association of Pathology Chairs Annual Meeting included a session for department chairs and other department leaders on "how to deal with deans and academic medical center leadership." The session was focused on discussing ways to foster positive relationships with university, medical school, and health system leaders, and productively address issues and opportunities with them. Presentations and a panel discussion were provided by 4 former pathology chairs who subsequently have served as medical deans and in other leadership positions including university provost, medical center CEO, and health system board chair. There was a strong consensus among the participants on how best to deal with superiors about problems, conflicts, and requests for additional resources and authority. The importance of teamwork and accountability in developing a constructive and collaborative relationship with leaders and peers was discussed in detail. Effectiveness in communication, negotiation, and departmental advocacy were highlighted as important skills. As limited resources and increased regulations have become growing problems for universities and health systems, internal stress and competition have increased. In this rapidly changing environment, advice on how chairs can interact most productively with institutional leaders is becoming increasingly important.
Publication
Journal: Journal of Colloid and Interface Science
July/1/2012
Abstract
Advanced synthetic methods under mild and controlled conditions for the synthesis of nanocrystals with specific shapes and exposed surfaces are very important for understanding the surface related properties and to explore their structure-property relationship for various potential applications. Here, we report the synthesis of highly uniform CeO(2) nanorods and nanoflowers in large scale using non-hydrothermal homogeneous precipitation method with urea as a precipitating agent and CTAB as a shape directing agent. Uniform microstructures of CeO(2) samples were selectively synthesized using chloride and nitrate as the counter anions. The samples were characterized by thermal analysis, X-ray diffraction, N(2) adsorption-desorption isotherms, SEM, TEM, UV-Vis-DRS, and Raman spectroscopy, and temperature programmed reduction as well as desorption methods. The results show that the physicochemical and optical properties of CeO(2) samples significantly differ with their surface microstructure and morphology. They also strongly influence the redox property, oxygen storage capacity, and surface acidity of the CeO(2) samples. The CeO(2) samples with different morphologies were tested for their soot oxidation activity. The CeO(2) sample with nanorod morphology was found to be more active due to larger CeO(2)/soot interface than the CeO(2) sample with nanoflower morphology.
Publication
Journal: Scientific Reports
October/10/2019
Abstract
This study describes a simple, high-yield, rapid, and inexpensive route for the synthesis of cubic shape-like cerium oxide nanocubes (CeO2 NCs) using different urea concentrations (0.5, 1.0, and 2.0 g) by the hydrothermal method. The synthesized nanocubes (NCs) are labeled as CeO2 NCs-0.5, CeO2 NCs-1.0, and CeO2 NCs-2.0, corresponding to 0.5, 1.0, and 2.0 g of urea, respectively. The synthesized NCs were characterized by FT-IR, UV-visible, XRD, XPS, SEM and HR-TEM analysis. The synthesized NCs were cubic in shape with average sizes of 12, 12, and 13 nm for the CeO2 NCs-0.5, CeO2 NCs-1.0, and CeO2 NCs-2.0, respectively, obtained by the XRD analysis. The catalytic activity of the CeO2 NCs was studied for the purpose of obtaining the reduction of malachite green (MG) in the presence of sodium borohydride (NaBH4) at room temperature.
Publication
Journal: Journal of Hazardous Materials
November/22/2018
Abstract
Herein, we report for the first time the highly efficient degradation of 2,4-dichlorophenol (2,4-DCP) over CeOCeO/CN) prepared via wet-chemical solution method. It is shown that the resultant nanocomposites with a proper mass ratio percentage (15%) of CeO coupled exhibit greatly enhanced visible-light activity for 2,4-dichlorophenol (2,4-DCP) degradation compared to the bare g-C3N4. From photoluminescence (PL) and Fluorescence (FL) results, it is suggested that enhanced photo-degradation is attributed to the significantly improved charge separation and transfer as a result of the proper band alignments between g-C3N4 and CeO components. Further, from radical trapping experiments, it is confirmed that hydroxyl radicals (OH) are the predominant oxidants involved in the degradation of 2,4-DCP over CeO/CN composites. Furthermore, a possible reaction pathway and detailed photocatalytic mechanism for 2,4-DCP degradation is proposed mainly based on the detected liquid chromatography tandem mass spectrometry (LC-MS) intermediate products, that readily transform into CO2 and H2O. This work would help researchers to deeply understand the reaction mechanism of 2,4-DCP and would provide feasible routes to fabricate g-C3N4-based highly efficient photocatalysts for environmental remediation.
Publication
Journal: Sensors
September/1/2020
Abstract
: The main purpose of this work is to study the effectiveness of using FeCeOx nanocomposites doped with Nb2O5 for the purification of aqueous solutions from manganese. X-ray diffraction, energy-dispersive analysis, scanning electron microscopy, vibrational magnetic spectroscopy, and mössbauer spectroscopy were used as research methods. It is shown that an increase in the dopant concentration leads to the transformation of the shape of nanoparticles from spherical to cubic and rhombic, followed by an increase in the size of the nanoparticles. The spherical shape of the nanoparticles is characteristic of a structure consisting of a mixture of two phases of hematite (Fe2O3) and cerium oxide CeO2. The cubic shape of nanoparticles is typical for spinel-type FeNbO4 structures, the phase contribution of which increases with increasing dopant concentration. It is shown that doping leads not only to a decrease in the concentration of manganese in model solutions, but also to an increase in the efficiency of adsorption from 11% to 75%.
Keywords: FeNbO4; chemical deposition; doping; nanocomposites; water purification.
Publication
Journal: Membranes
March/5/2021
Abstract
CeOx hybrid nanoparticles were synthesized and evaluated for use as radical scavengers, in place of commercially available Ce(NO3)3 and CeO2 nanoparticles, to avoid deterioration of the initial electrochemical performance and/or spontaneous aggregation/precipitation issues encountered in polymer electrolyte membranes. When CeOx hybrid nanoparticles were used for membrane formation, the resulting membranes exhibited improved proton conductivity (improvement level = 2-15% at 30-90 °C), and thereby electrochemical single cell performance, because the -OH groups on the hybrid nanoparticles acted as proton conductors. In spite of a small amount (i.e., 1.7 mg/cm3) of introduction, their antioxidant effect was sufficient enough to alleviate the radical-induced decomposition of perfluorinated sulfonic acid ionomer under a Fenton test condition and to extend the chemical durability of the resulting reinforced membranes under fuel cell operating conditions.
Keywords: polymer electrolyte membrane; radical scavenger; service life.
Publication
Journal: Environmental Pollution
December/21/2018
Abstract
Heavy metals and emerging engineered nanoparticles (ENPs) are two current environmental concerns that have attracted considerable attention. Cerium oxide nanoparticles (CeO2NPs) are now used in a plethora of industrial products, while cadmium (Cd) is a great environmental concern because of its toxicity to animals and humans. Up to now, the interactions between heavy metals, nanoparticles and plants have not been extensively studied. The main objectives of this study were (i) to determine the synergistic effects of Cd and CeO2NPs on the physiological parameters of Brassica and their accumulation in plant tissues and (ii) to explore the underlying physiological/phenotypical effects that drive these specific changes in plant accumulation using Artificial Neural Network (ANN) as an alternative methodology to modeling and simulating plant uptake of Ce and Cd. The combinations of three cadmium levels (0 [control] and 0.25 and 1 mg/kg of dry soil) and two CeO2NPs concentrations (0 [control] and 500 mg/kg of dry soil) were investigated. The results showed high interactions of co-existing CeO2NPs and Cd on plant uptake of these metal elements and their interactive effects on plant physiology. ANN also identified key physiological factors affecting plant uptake of co-occurring Cd and CeO2NPs. Specifically, the results showed that root fresh weight and the net photosynthesis rate are parameters governing Ce uptake in plant leaves and roots while root fresh weight and Fv/Fm ratio are parameters affecting Cd uptake in leaves and roots. Overall, ANN is a capable approach to model plant uptake of co-occurring CeO2NPs and Cd.
Publication
Journal: Materials
August/12/2017
Abstract
Despite the increasing use of rare earth elements (REEs) and oxides (REOs) in various technologies, the information on their ecotoxicological hazard is scarce. Here, the effects of La3+, Ce3+, Pr3+, Nd3+, Gd3+, CeO₂, and eight doped REOs to marine bacteria Vibrio fischeri and freshwater protozoa Tetrahymena thermophila were studied in parallel with REO dopant metals (Co2+, Fe3+, Mn2+, Ni2+, Sr2+). The highest concentrations of REOs tested were 100 mg/L with protozoa in deionized water and 500 mg/L with bacteria in 2% NaCl. Although (i) most REOs produced reactive oxygen species; (ii) all studied soluble REEs were toxic to bacteria (half-effective concentration, EC50 3.5-21 mg metal/L; minimal bactericidal concentration, MBC 6.3-63 mg/L) and to protozoa (EC50 28-42 mg/L); and (iii) also some dopant metals (Ni2+, Fe3+) proved toxic (EC50 ≤ 3 mg/L), no toxicity of REOs to protozoa (EC50>> 100 mg/L) and bacteria (EC50>> 500 mg/L; MBC>> 500 mg/L) was observed except for La₂NiO₄ (MBC 25 mg/L). According to kinetics of V. fischeri bioluminescence, the toxicity of REEs was triggered by disturbing cellular membrane integrity. Fortunately, as REEs and REOs are currently produced in moderate amounts and form in the environment insoluble salts and/or oxides, they apparently present no harm to aquatic bacteria and protozoa.
Publication
Journal: Journal of Food Science and Technology
July/27/2017
Abstract
Spices are well known for their taste and flavor imparting properties. Green cardamom (Elletaria cardamomum), a herb spice belongs to family Zingiberaceae. In current study, GC-MS analysis of green cardamom essential oil (CEO) resulted in identification of twenty-six compounds with α-terpinyl acetate (38.4%), 1,8-cineole (28.71%), linalool acetate (8.42%), sabinene (5.21%), and linalool (3.97%) as major bioactive components. Present study also described the antimicrobial properties like zone of inhibition, minimum inhibitory concentration against microbial strains with special emphasis on quorum sensing inhibition. Disk diffusion assay showed that C. albicans and S. mutans were the most sensitive microorganisms followed by S. aureus, L. monocytogenes, B. cereus and S. typhimurium sensor strains, respectively. Whilst P. aeruginosa was found most resistant strain as CEO did not inhibited its growth. The minimum inhibitory concentration (MIC) values of CEO against tested strains were 10 ± 0.00 mg/mL against S. typhimurium, S. aureus and 5 ± 0.00 mg/mL against S. mutans, C. albicans strains, respectively. Regarding quorum sensing inhibition the tested concentrations 0.625 and 0.313 mg/mL of CEO inhibited violacein production with very little effect on growth of C. violaceum. Conclusively, study proved that quorum sensing inhibition values of CEO were much lower compared to MIC revealed values. Hence, cardamom bioactive constituents can effectively be used to develop novel antimicrobial drugs against conventional antibiotics.
Publication
Journal: Biological Trace Element Research
August/15/2019
Abstract
Cerium(IV) oxide is widely used as a catalyst in all aspects of human life and human beings are exposed to these materials. The purpose of this experimental study was to investigate the effect of CeO2 during pregnancy on alterations in the testis tissue and blood biochemical parameters in newborn mice. Pregnant NMRI mice were divided randomly into five groups (n = 6 for each group) including one control group and 4 treatment groups. Injection of CeO2 solution was administered intraperitoneally at the doses of 10, 25, 80, and 250 mg/kg.bw, respectively, on GD 7 and GD 14. At the end of treatment period, the testicular histological and biochemical parameters of 2- and 6-day-old newborns were analyzed, as well as the biochemical parameters in serum samples of 15-day-old newborns. The number of spermatogonia, Sertoli, and Leydig cells in the testis of the 2-day-old newborn and spermatogonia and Leydig cells in the testis of the 6-day-old newborns in the 250 mg/kg.bw CeO2 treatment group was significantly reduced compared with the control group (P < 0.05). Testis MDA of the 2- and 6-day-old newborns in the treated group receiving 250 mg/kg.bw of CeO2 was significantly higher than the control group (P < 0.001). There was no significant difference between serum MDA and TAC levels between the treated groups with different doses of CeO2 compared with the control group. Therefore, CeO2 given to dams during pregnancy may affect the testicular tissue and blood biochemical parameters in neonates and may be dose-dependent.
Publication
Journal: Biomolecules
September/6/2019
Abstract
The world of medicinal therapies has been historically, and remains to be, dominated by the use of elegant organic molecular structures. Now, a novel medical treatment is emerging based on CeO2 nano-crystals that are discrete clusters of a few hundred atoms. This development is generating a great deal of exciting and promising research activity, as evidenced by this Special Issue of Biomolecules. In this paper, we provide both a steady-state and time-dependent mathematical description of a sequence of reactions: superoxide generation, superoxide dismutase, and hydrogen peroxide catalase and ceria regeneration. This sequence describes the reactive oxygen species (ROS); superoxide, O2-, molecular oxygen, O2, hydroxide ion OH- and hydrogen peroxide, H2O2, interacting with the Ce3+, and Ce4+ surface cations of nanoparticle ceria, CeO2. Particular emphasis is placed on the predicted time-dependent role of the Ce3+/Ce4+ ratio within the crystal. The net reaction is succinctly described as: H2O2 + 2O2- + 2H+ → 2H2O + 2O2. The chemical equations and mathematical treatment appears to align well with several critical in vivo observations such as; direct and specific superoxide dismutase (SOD), ROS control, catalytic regeneration, ceria self-regulation and self-limiting behavior. However, in contrast to experimental observations, the model predicts that the 4+ ceric ion state is the key SOD agent. Future work is suggested based on these calculations.
Publication
Journal: Biomolecules
August/20/2019
Abstract
Pulmonary exposure to cerium oxide nanoparticles (CeO2 NPs) can occur either at the workplace, or due to their release in the environment. Inhaled CeO2 NPs are known to cross the alveolar-capillary barrier and reach various parts of the body, including the vasculature. The anticancer drug cisplatin (CP) causes vascular damage. However, the effects CeO2 NPs on vascular homeostasis in a rat model of CP-induced vascular injury remain unclear. Here, we assessed the impact and underlying mechanism of pulmonary exposure to CeO2 NPs on aorta in rats given a single intraperitoneal injection of cisplatin (CP, 6 mg/kg) to induce vascular damage. Six days later, the rats were intratracheally instilled with either CeO2 NPs (1 mg/kg) or saline (control), and various variables were studied 24 h thereafter in the aortic tissue. The concentration of reduced glutathione and the activity of catalase were significantly increased in the CP + CeO2 NPs group compared with both the CP + saline and the CeO2 NPs groups. The activity of superoxide dismutase was significantly decreased in the CP + CeO2 NPs group compared with both the CP + saline and CeO2 NPs groups. The expression of nuclear factor erythroid-derived 2-like 2 (Nrf2) by the nuclei of smooth muscles and endocardial cells assessed by immunohistochemistry was significantly augmented in CeO2 NPs versus saline, in CP + saline versus saline, and in CP + CeO2 NPs versus CeO2 NPs. Moreover, the concentrations of total nitric oxide, lipid peroxidation and 8-hydroxy-2-deoxyguanosine were significantly elevated in the CP + CeO2 NPs group compared with both the CP + saline and the CeO2 NPs groups. Similarly, compared with both the CP + saline and CeO2 NPs groups, the combination of CP and CeO2 NPs significantly elevated the concentrations of interleukin-6 and tumour necrosis factor-α. Additionally, aortic DNA damage assessed by Comet assay was significantly increased in CeO2 NPs compared with saline, and in CP + saline versus saline, and all these effects were significantly aggravated by the combination of CP and CeO2 NPs. We conclude that pulmonary exposure to CeO2 NPs aggravates vascular toxicity in animal model of vascular injury through mechanisms involving oxidative stress, Nrf2 expression, inflammation and DNA damage.
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